It is well known that each layer of a double journal paper roll does not unwind at the same rate from a single supply roll. The difference in unwinding rate occurs because the outside paper layer lies at a greater radius and therefore has a larger circumference. When these two layers of journal paper are passed through feed rolls of a printer, the outer layer becomes loose around the supply roll. This looseness is called blousing. If the loose outer layer is contained tightly in the supply chamber, it will wrinkle and cause paper feeding jams. If the loose outer layer is allowed to expand without restriction, it may interfere with other mechanisms such as the takeup reel. Blousing is increased when the inner paper layer is wound on a takeup reel as the master journal and the outer paper layer is fed by friction to be torn off and used by the printer operator for such purposes as reconciling a cash drawer.
It is also recognized that the automatic sensing of exhausted paper is made more difficult when two layers of journal paper are simultaneously unwound from a single supply roll. Directly sensing an out of paper condition is made more difficult because both layers of paper from a double journal supply roll are not exhausted at the same time due to the problem of blousing described above. When the inner layer of journal paper is used as the master journal, it is usually covered by the outer layer and not visible to the operator. Because the inner layer of paper is a shorter web when unwound from a single supply reel, the inner layer is exhausted first. Because the inner layer is covered by the outer layer when viewed by the operator, the exhaustion of the inner layer master journal is not easy to notice by the operator. Because the outer layer is not exhausted, direct automatic sensing would require that the variation in thickness from a double layer to a single layer be detected.
One solution to the problem of blousing paper from a dual web supply roll is to eliminate the dual web supply roll and substitute therefor two single layer supply rolls. Providing separate supply rolls is effective but requires extra space and cost. Another attempt at solving the problem of blousing is described in U.S. Pat. No. 2,510,626. As can be seen from FIG. 3 of this patent, the outer layer having tendency to blouse is used as the master journal. The master journal takeup reel then provides tension tending to reel in the extra length of the outer layer. A problem is presented by U.S. Pat. No. 2,510,626 however in that the paper develops a curl while on the supply roll. This curl is such that the teller's audit journal which exits from the machine tends to curl forward toward the operator. The forward curl makes insertion of cut forms inconvenient and time consuming.
A different approach is described in U.S. Pat. No. 2,998,905. In this patent, feed wheel 10 acting on the outer layer 6' is made to rotate faster than platen 1 which is in contact with the inner layer. The outer layer 6' is then pushed upward faster than inner layer 6. Such difference in rotation speed may cause some papers to be marked by the feed wheel. Another potential problem is that depending upon variation in paper thickness etc., the difference in feed wheel speed may cause the inner layer to blouse.